Snorkelers breathe through tubes that extend above the surface of the water. in prin- ciple, a snorkeler could go deeper with a longer tube, but the extra pressure at the greater depth would make breathing too difficult. if a snorkeler can develop a pressure in her lungs that is 10 kpa below the pressure outside her body, what is the longest snorkel she could use in the ocean?

h = 1.02 m

Explanation:

This is a fluid mechanics exercise, where the pressure is given by

       P = + ρ g h

The gauge pressure is

      P -  = ρ g h

In this case the upper part of the tube we have the atmospheric pressure. and the diver can exert a pressure 10 KPa below the outside pressure, this must be the gauge pressure

      =    P -

      = ρ g h

     h = / ρ g

calculate

     h = 10 103 / (1000 9.8)

     h = 1.02 m

This is the depth at which man can breathe

i think the answer would be b

frequency or wavelenth of em radiation in a vacuum